scholarly journals Close stellar encounters with the Sun from the first Gaia Data Release

2017 ◽  
Vol 12 (S330) ◽  
pp. 144-147
Author(s):  
Coryn A. L. Bailer-Jones
Keyword(s):  
The Sun ◽  
Preliminary Results ◽  
Data Release

AbstractI present preliminary results of searching for close stellar encounters with the Sun using the first Gaia data release. Gl 710 is found to be a much closer encounter than found in pre-TGAS studies. More detailed results will be reported in an upcoming publication (Bailer-Jones 2017, in preparation).

scholarly journals I.—Secular Earth-Creep

1909 ◽  
Vol 6 (4) ◽  
pp. 145-148 ◽  
Author(s):  
E. H. L. Schwarz
Keyword(s):  
South Africa ◽  
Diurnal Variation ◽  
Royal Society ◽  
The Sun ◽  
Special Design ◽  
Important Paper ◽  
Preliminary Results ◽  
Gravitational Pull ◽  
Set Up ◽  
Horizontal Pendulum

Dr. J. R. Sutton has recently read a most important paper to the Royal Society of South Africa on the diurnal variation of level at Kimberley. The paper gave the preliminary results of observations made during the course of three years upon the variation of the level of the ground as recorded by a large horizontal pendulum of a special design made for the author by the Cambridge Instrument Company. It appeared from the results that the movements in the surface of the ground, which set up corresponding movements in the pendulum, were very great. The maximum westerly elongation of the extremity of the pendulum occurred about 5.30 a.m., the maximum easterly about 4.15 p.m., the medium positions a little before 11 a.m. and 9.30 p.m. Geometrically these movements may be represented on the hypothesis that the hemisphere facing the sun bulges out, forming a sort of meniscus to the geosphere. The rise and fall of the surface of the ground which such a supposition would postulate is enormous, and the very magnitude has led Dr. Sutton to hesitate in giving the figures. There can, however, be very little doubt that some rise and fall in the earth's surface is occasioned by the sun's gravitational pull, although the present figures may have to be lessened by taking into consideration other causes which contribute to the disturbance of the pendulum.

scholarly journals Search for stellar companions of exoplanet host stars by exploring the second ESA-Gaia data release

2019 ◽  
Vol 490 (4) ◽  
pp. 5088-5102 ◽  
Author(s):  
M Mugrauer
Keyword(s):  
Main Sequence ◽  
Stellar Systems ◽  
Sequence Evolution ◽  
The Sun ◽  
M Dwarfs ◽  
Primary Star ◽  
True Nature ◽  
Quadruple System ◽  
Data Release ◽  
Host Stars

ABSTRACT A new survey is presented, which explores the second data release of the ESA-Gaia mission, in order to search for stellar companions of exoplanet host stars, located at distances closer than about 500 pc around the Sun. In total, 176 binaries, 27 hierarchical triples, and one hierarchical quadruple system are detected among more than 1300 exoplanet host stars, whose multiplicity is investigated, yielding a multiplicity rate of the exoplanet host stars of at least about 15  per cent. The detected companions and the exoplanet host stars are equidistant and share a common proper motion, as it is expected for gravitationally bound stellar systems, proven with their accurate Gaia astrometry. The companions exhibit masses in the range between about 0.078 and 1.4 M⊙ with a peak in their mass distribution between 0.15 and $0.3\, \mathrm{M}_{\odot }$. The companions are separated from the exoplanet host stars by about 20 up to 9100 au, but are found most frequently within a projected separation of 1000 au. While most of the detected companions are early M dwarfs, eight white dwarf companions of exoplanet host stars are also identified in this survey, whose true nature is revealed with their photometric properties. Hence, these degenerated companions and the exoplanet host stars form evolved stellar systems with exoplanets, which have survived (physically but also dynamically) the post-main-sequence evolution of their former primary star.

scholarly journals Testing for Dark Matter in the Outskirts of Globular Clusters

2021 ◽  
Vol 922 (2) ◽  
pp. 104
Author(s):  
Raymond G. Carlberg ◽  
Carl J. Grillmair
Keyword(s):  
Dark Matter ◽  
Globular Clusters ◽  
High Probability ◽  
Velocity Dispersion ◽  
High Redshift ◽  
Dark Matter Halo ◽  
The Sun ◽  
Proper Motions ◽  
Preliminary Results ◽  
Galactic Background

Abstract The proper motions of stars in the outskirts of globular clusters are used to estimate cluster velocity dispersion profiles as far as possible within their tidal radii. We use individual color–magnitude diagrams to select high-probability cluster stars for 25 metal-poor globular clusters within 20 kpc of the Sun, 19 of which have substantial numbers of stars at large radii. Of the 19, 11 clusters have a falling velocity dispersion in the 3–6 half-mass radii range, 6 are flat, and 2 plausibly have a rising velocity dispersion. The profiles are all in the range expected from simulated clusters that started at high redshift in a zoom-in cosmological simulation. The 11 clusters with falling velocity dispersion profiles are consistent with no dark matter above the Galactic background. The six clusters with approximately flat velocity dispersion profiles could have local dark matter, but are ambiguous. The two clusters with rising velocity dispersion profiles are consistent with a remnant local dark matter halo, but need membership confirmation and detailed orbital modeling to further test these preliminary results.

scholarly journals IUE Observations of WZ Sagittae in Outburst

1980 ◽  
Vol 88 ◽  
pp. 447-451 ◽  
Author(s):  
Albert V. Holm ◽  
Chi-Chao Wu ◽  
Warren M. Sparks ◽  
Francis H. Schiffer ◽  
Albert Boggess
Keyword(s):  
Accretion Disk ◽  
The Sun ◽  
Dwarf Novae ◽  
Low Resolution ◽  
Preliminary Results ◽  
International Ultraviolet Explorer ◽  
Recurrent Nova

The International Ultraviolet Explorer was used to obtain spectra at both 7 Å and 0.2 Å resolution of the recurrent nova WZ Sagittae during its 1978 outburst. The first spectra were obtained on 1978 Dec 1.8 UT, approximately 0.7 days after discovery. The decay from outburst was followed until 1979 Jan 1, after which it was too near the Sun to be observed. A post-outburst spectrum was obtained on 1979 July 11. In this paper, preliminary results from the analysis of the low resolution spectra are discussed. These observations will be used to support the similarity between WZ Sge and dwarf novae and to test accretion disk models.

scholarly journals MKJ and MSS Classification of Solar-Type Stars Within 100 Parsecs of the Sun: Preliminary Results

1985 ◽  
Vol 111 ◽  
pp. 407-410
Author(s):  
M. Fracassini ◽  
L. E. Pasinetti ◽  
M. Borella ◽  
A. Pasinetti
Keyword(s):  
Spectral Type ◽  
Selection Criteria ◽  
The Sun ◽  
Preliminary Results ◽  
Good Selection ◽  
Color Indices ◽  
Solar Type

A study of the distribution of spectral types of Solar Type Stars (STS) in the revised MKJ and MSS classifications is made on 3919 F8-K3 HD spectral-type stars brighter than mv=10. By means of the solar color indices U-B and B-V 697 STS were selected. The spectral types G3V and G5V have the highest percentages in MSS and MKJ, respectively, confirming statistically the results published by Keenan and Pitts (1980) and by Hardorp (1982). The distribution of the color indices U-B and B-V in the revised G2V spectral type shows that these are good selection criteria for STS and are in the range 0.06 ≤ U-B ≤ 0.10 and 0.58 ≤ B-V ≤ 0.65.

A scanning X-ray spectroheliograph

1970 ◽  
Vol 317 (1528) ◽  
pp. 101-112 ◽  
Keyword(s):  
Proportional Counter ◽  
Grazing Incidence ◽  
The Sun ◽  
Design And Development ◽  
X Ray ◽  
Preliminary Results

A grazing incidence reflector which focuses radiation on to a proportional counter has been used to obtain X -ray pictures of the Sun in a number of relatively narrow wavelength bands below 2 nm. The design and development of the instrument is discussed together with the preliminary results from two rocket flights.

scholarly journals The Sun at the VLA's Metric and Decimetric Wavelengths

1990 ◽  
Vol 142 ◽  
pp. 523-524
Author(s):  
S. M. White ◽  
M. R. Kundu ◽  
N. Gopalswamy ◽  
E. J. Schmahl
Keyword(s):  
Large Scale ◽  
Dynamic Range ◽  
Active Regions ◽  
High Dynamic Range ◽  
The Sun ◽  
Large Array ◽  
Very Large Array ◽  
Preliminary Results ◽  
High Dynamic ◽  
Coronal Structures

During September 1988 (International Solar Month) we observed the Sun with the Very Large Array on 4 days in the period Sep. 11-17. The VLA was in its most compact configuration, which is ideal for studying large-scale coronal structures. Here we summarize some preliminary results of the observations at 0.333 and 1.5 GHz. Despite the presence of numerous active regions the Sun was actually very quiet, with no flares during our observing, and this allowed us to make high-dynamic-range maps.

scholarly journals Determining the mass of the planetary candidate HD 114762 b using Gaia

2019 ◽  
Vol 632 ◽  
pp. L9 ◽  
Author(s):  
Flavien Kiefer
Keyword(s):  
Spectral Analysis ◽  
Preceding Paper ◽  
Brown Dwarfs ◽  
Excess Noise ◽  
The Sun ◽  
Minimum Mass ◽  
Brown Dwarf ◽  
Data Release ◽  
Low Mass ◽  
M Dwarf

The first planetary candidate discovered by Latham et al. (1989, Nature, 339, 38) with radial velocities around a solar-like star other than the Sun, HD 114762 b, was detected with a minimum mass of 11 MJ. The small v sin i ∼ 0 km s−1 that is otherwise measured by spectral analysis indicated that this companion of a late-F subgiant star better corresponds to a massive brown dwarf (BD) or even a low-mass M-dwarf seen nearly face-on. To our knowledge, the nature of HD 114762 b is still undetermined. The astrometric noise measured for this system in the first data release, DR1, of the Gaia mission allows us to derive new constraints on the astrometric motion of HD 114762 and on the mass of its companion. We use the method GASTON, introduced in a preceding paper, which can simulate Gaia data and determine the distribution of inclinations that are compatible with the astrometric excess noise. With an inclination of 6.26.2+1.9−1.3 degree, the mass of the companion is constrained to Mb = 108+31−26 MJ. HD 114762 b thus indeed belongs to the M-dwarf domain, down to brown dwarfs, with Mb >  13.5 MJ at the 3σ level, and is not a planet.

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